Oil or other fluid cargo can be transferred between an undersea pipeline and a vessel, through a single point mooring terminal that includes a buoy floating at the surface of the sea and anchored in place by several catenary chains. The buoy serves as a transfer structure, and is coupled by a hose or pipe to the undersea pipeline and by another hose or pipe to a floating vessel. In some applications, it has been found useful to permanently moor a storage vessel to the buoy. A variety of mooring structures have been utilized to connect the buoy, or transfer structure, to a permanently moored vessel. One type of mooring terminal, such as that shown in U.S. Pat. No. 3,335,690 by Busking, utilizes a beam rigidly fixed to the vessel and to a rotatable portion of the transfer structure. In this type of terminal, the buoyancy of the vessel supports the transfer structure, and a nonrotatable portion of the transfer structure holds the vessel in approximate location by means of chains that exend from the transfer structure to the sea floor. The transfer structure can lie out of the water to facilitate access to a swivel unit, or product distribution unit (PDU), on the transfer structure, which is a device that typically requires maintenance, to facilitate such maintenance. However, as is pointed out in "The Advantages of the Single Buoy Storage System (SBS)" by Sagot and Van Heijst in a paper given at the fifth annual Offshore Technology Conference held in Houston, Tex. Apr. 29-May 2, 1973, there are several disadvantages in this rigid mooring approach. These disadvantages include the fact that the transfer structure is subject to high pitch motions and the hose that extends down to the sea base is subjected to wave motions that can damage it. Also, the beam which holds the transfer structure must be very strong in order to hold the transfer structure a considerable distance away from the vessel to avoid the chains hitting the vessel. A mooring installation of the type which utilized a transfer structure rigidly connected to an end of a vessel, but which avoided many of the disadvantages of prior art installations of this type, would be of considerable value.